Violent attacks have erupted at airports across China, with passengers venting their rage on hapless staff over a summer of grinding delays.

China has spent billions on building some of the largest and most modern airports in the world, but, much to everyone’s embarrassment, it seems unable to get planes to fly between them on time.

Last month, only 18 per cent of the 22,000 flights out of Beijing’s Capital airport departed on schedule, according to the aviation research company FlightStats, making it the world’s worst major airport for punctuality. Not one Chinese airport managed to get even half of its flights to leave on time.

The delays have seen mobs of angry passengers mount at least eight large protests at departure gates in the past two months, during two of which staff were attacked. There is even a new Chinese phrase for the rampaging hordes: the “kong nu zu”, or “air rage tribe”.

The other passengers were applauding as the man was hitting her

On Thursday July 18, more than 30 passengers broke through security and stormed the runway at Nanchang airport after being delayed for seven hours by bad weather.

The weekend before, passengers in Shanghai tried to rip off an attendant’s name badge before hitting her. In the subsequent fracas, two airport staff were injured and three passengers arrested. “The passengers were very emotional and unstable,” Ni Xuying, one of the injured employees, told state television.

At the end of June, a primary school teacher lost control when her flight from Wenzhou to Beijing was cancelled, slapping and kicking an Air China attendant to the ground. “I waited there for such a long time. Nobody served me a bottle of water or a piece of cake or anything,” Liu Weiwei said in her defence.

In March, Graham Fewkes, a British businessman based in Hong Kong, told the South China Morning Post he had witnessed cheers when a passenger assaulted a stewardess on a delayed flight to the island of Sanya.

“The other passengers were applauding as the man was hitting her,” he said.

Hong Kong Airlines last year said it had an average of three incidents involving disruptive passengers every week and has introduced training in wing chun, a form of kung fu, for its cabin crew.

The situation at China’s airports is now so volatile that staff have been told not to announce any major delays.

The problems have been caused by a sudden surge in air traffic, flowing into skies that are tightly controlled by the People’s Liberation Army. With only a few permitted routes, issues such as bad weather often force airlines to hold back flights rather than divert them.

The heavy delays are exacting an economic cost. Marco Pearman-Parish at Corporation China, a consultancy that helps companies establish a presence in China, said some 60 per cent of his clients at a recent meeting were considering moving their operations away from Beijing because of the constant problems at the airport. “The delays are making it impossible to do business,” he said.